Prince William, Duke of Cambridge has been appointed personal Aide-de-Camp to Her Majesty.
The Court Circular stated that the Queen “has been pleased to appoint The Duke of Cambridge as a personal Aide-de-Camp to Her Majesty” with immediate effect. His Royal Highness wore the insignia of an aide-de-camp for the first time at the St Patrick’s Day parade for the 1st Battalion Irish Guards at Mons Barracks in Hampshire.
A Personal Aide-de-Camp is a senior officer of the military of a Commonwealth Realm who is appointed to act as the honorary military attendant to the Monarch and/or her viceroys.
Prince William is the seventh member of the Royal Family who currently holds the appointment, the others being The Duke of Kent (Field Marshal), the Prince of Wales (Admiral of the Fleet), Mark Phillips (Captain, Retired), The Duke of York (Rear-Admiral), The Earl of Wessex (Second Lieutenant), and Sir Timothy Laurence (Vice Admiral).
Although Prince William’s military rank is Flight Lieutenant, his appointment lists him as a Colonel. That is due to the fact that members of the Royal Family are appointed based on the highest (honorary or otherwise) military rank they hold, and the Duke of Cambridge has been Colonel of the Irish Guards since February of 2011.